1. Field of the Invention
The present invention relates to an articulated robot like a legged robot having at least limbs and a trunk, and a method of controlling the motion of the articulated robot, and, more particularly, to a legged robot which executes various motion patterns by using the limbs and/or the trunk, and a method of controlling the motion of the legged robot.
Still more particularly, the present invention relates to a legged robot which communicates by moving the limbs and/or the trunk, and a method of controlling the motion of the legged robot. Even still more particularly, the present invention relates to a legged robot which comes to an understanding through various motion patterns making use of the limbs and/or the trunk, and a method of controlling the motion of the legged robot.
2. Description of the Related Art
A robot is a mechanical device which emulates the motion of a human being by making use of electrical and magnetic actions. The term robot is said to be derived from the Slavic word ROBOTA (slavish machine). In our country, the widespread use of robots began from the end of the 1960s, many of which were industrial robots, such as manipulators and conveyance robots, used, for example, for the purpose of achieving automatic industrial operations in factories without humans in attendance.
Installation-type robots, such as arm-type robots, which are provided so as to be implanted at a particular place function only in fixed/localized working spaces for carrying out parts assembly/sorting and the like. In contrast, mobile robots can function in unlimited working spaces, so that they can freely move in predetermined paths or pathless areas in order to perform in place of human beings a predetermined or a desired human task, or to provide various wide-ranging services in place of living beings such as humans and dogs. Of the mobile robots, legged mobile robots are unstable compared to crawler-type robots and wheeled robots, so that it becomes difficult to control their posture and walking. However, legged mobile robots are excellent robots in that they can move up and down steps and ladders, go over obstacles, and walk/run flexibly regardless of whether the ground is leveled or unleveled.
In recent years, advances have been made in the research and development of legged mobile robots such as pet robots and humanoid robots, with pet robots emulating the mechanism of the body of an animal which moves using four legs, such as a dog or a cat, and the motion thereof, and with humanoid robots being designed using as a model the mechanism of the body of an animal which moves erect using two legs, such as a human being, and the motion thereof. Therefore, there is increasing expectations for putting such robots into practical use.
The significance of carrying out research and development on legged mobile robots called humanoid robots can be understood from, for example, the following two viewpoints.
The first viewpoint is related to human science. More specifically, through the process of making a robot having a structure which is similar to that having lower limbs and/or upper limbs of human beings, thinking up a method of controlling the same, and simulating the walking of a human being, the mechanism of the natural motion of a human being, such as walking, can be ergonomically understood. The results of such research can considerably contribute to the development of other various research fields which treat human motion mechanisms, such as ergonomics, rehabilitation engineering, and sports science.
The other viewpoint is related to the development of practical robots as partners of human beings which help them in life, that is, help them in various human activities in situations in living environments and in various other situations in everyday life. Functionally, in various aspects of the living environment of human beings, these robots need to be further developed by learning methods of adapting to environments and acting in accordance with human beings which have different personalities and characters while being taught by human beings. Here, it is believed that making the form and structure of the robot the same as those of a human being is effective in achieving smooth communication between the robot and a human being.
For example, when teaching a robot a way of passing through a room by avoiding obstacles which should not be stepped on, it is much easier for the user (worker) to teach it to a robot which walks using two legs having the same form as the user than a crawler-type or a robot which walks using four legs having a completely different structure from the user. In this case, it must also be easier for the robot to learn it (Refer to, for example, xe2x80x9cControlling a Robot Which Walks Using Two Legsxe2x80x9d by Takanishi (Jidosha Gijutsukai Kanto Shibu  less than Koso greater than  No. Apr. 25, 1996).
The working space and living space of human beings are formed in accordance with the behavioral mode and the body mechanism of a human being which walks erect using two legs. In other words, for moving present wheeled mechanical systems or other such driving devices as moving means, the living space of human beings has too many obstacles. It is preferable that the movable range of the robot be about the same as that of human beings in order for the mechanical system, that is, the robot to carry out various human tasks in place of them, and to deeply penetrate the living space of human beings. This is the reason why there are great expectations for putting a legged mobile robot into practical use. In order to increase the capability of the robot to exist harmoniously in the living environment of human beings, it is essential for the robot to possess a human form.
Humanoid robots can be used to carry out various difficult operations, such as in industrial tasks or production work, in place of human beings. They carry out in place of human beings dangerous or difficult operations at places where human beings cannot easily step into, such as maintenance work at nuclear power plants, thermal power plants, or petrochemical plants, parts transportation/assembly operations in manufacturing plants, cleaning of tall buildings, rescuing of people at places where there is a fire, and the like.
Humanoid robots can also be used xe2x80x9cto live togetherxe2x80x9d in the same living space as human beings, that is, for entertainment purposes. In this application, the robot is characterized more as being closely related to life rather than as helping human beings in life such as performing tasks in place of them.
The theme of entertainment robots is the research and development of the motion patterns which are executed during a task rather than realizing specific industrial purposes at high speeds and with high precision. In other words, it is preferable for the entertainment robots to faithfully reproduce the mechanism which allows harmonious movement of the whole body possessed by nature by animals which walk erect using two legs, such as human beings and monkeys, and to make them realize this natural and smooth movement. In emulating a highly intelligent animal which stands erect, such as human beings and monkeys, it is to be considered that a motion pattern using the four limbs is natural for a living body, and that it is desirable that the motions are sufficiently indicative of emotions and feelings.
Further, entertainment robots are required not only to faithfully execute a previously input motion pattern, but also to express its feelings by moving in a lively manner in response to the words and actions of a person (such as speaking highly of someone, scolding someone, or hitting someone). In this sense, entertainment robots which emulate human beings are rightly called humanoid robots.
In conventional toy machines, the relationship between the operations which are carried out by the user and the response motion is fixed/standardized, so that the same motion is merely repeated, causing the user to eventually get tired of the toy machines. In contrast, entertainment robots, though they move in accordance with a motion generation time series model, can change this time series model, that is, impart a learning effect, in response to the detection of an external stimulus which is produced by, for example, the operation of the user. Therefore, the relationship between the operations which are carried out by the user and the responding motion is programmable, making it possible to provide a motion pattern which does not make the user tired of it or which conforms to the preferences of the user. In addition, by operating the robot, the user can enjoy a type of educational simulation.
A robot is made to operate to, for example, perform certain xe2x80x9ctasksxe2x80x9d such as parts assembly, or to xe2x80x9cmovexe2x80x9d to, for example, transport things. Therefore, the robot is basically a means for achieving a specific result.
In entertainment robots where human beings and pets are used as models, the word xe2x80x9ctaskxe2x80x9d has a wider meaning, so that, in addition to including industrial and production activities, it also includes the execution of entertainment motion patterns such as xe2x80x9cdancingxe2x80x9d and xe2x80x9cgreeting someone.xe2x80x9d Further, the range of tasks using the legs extend from those including motion patterns which are executed merely for the purpose of xe2x80x9cmovingxe2x80x9d from place to place to those which include motion patterns which involve high-speeds and are strongly characterized as entertainment motion patterns, such as running and jumping.
However, these tasks which are executed by entertainment robots are similarly confined to being carried out to achieve particular results.
Other than for purposes for achieving a certain result, human beings move for conversational purposes, such as making gestures and waving the hands. Such conversational motions make it possible for human beings to understand each other using the sense of sight. The observer of the motion pattern can intuitively understand the meaning of the motion pattern of the other person, thereby making it unnecessary to communicate through words or to interpret words. For example, even if the two people use different languages, they can understand each other""s intentions using motion patterns even if they do not understand each other""s language very well. In other words, communication by a motion may at times make it possible for people to smoothly understand each other.
In contrast to this, a robot is basically a mechanical device, and can communicate with external devices at high speeds and with high precision through a predetermined communications medium by following a predetermined communications protocol. The term external device used here may be another robot or a host computing machine system for generating a command to a robot or for controlling the motion of the robot. In recent years, data communications technologies by wire or by radio have improved, so that one or more communications interfaces can be installed in the robot device.
However, robots cannot be made to understand each other unless the proper communications interface or protocols are used.
Compared to other types of robots such as arm robots and crawler robots, robots which having four relatively long limbs, such as humanoid robots, have a much higher degree of freedom provided by joints. However, this high degree of freedom has not been positively made use of in realizing communication by a motion of the robot 100.
Accordingly, it is an object of the present invention to provide an excellent legged robot comprising at least limbs and a trunk, and a method of controlling the motion of the legged robot.
It is another object of the present invention to provide an excellent legged robot which can execute various motion patterns using the limbs and/or the trunk, and a method of controlling the motion of the legged robot.
It is still another object of the present invention to provide an excellent legged robot which can communicate by moving the limbs and/or the trunk, and a method of controlling the motion of the legged robot.
It is still another object of the present invention to provide an excellent legged robot which through various motion patterns using the limbs and/or the trunk can come to an understanding with the external world such as robots which have not been connected through data transmission media, and a method of controlling the motion of the legged robot.
In view of the above-described problems, according to a first aspect of the present invention, there is provided an articulated robot which comprises a plurality of joints. The articulated robot includes a movement controller for controlling the movement of each of the joints, a motion language accumulator for accumulating a motion language formed by a motion pattern of the joints, and a movement output controller for giving the motion language to be used to the movement controller as a result of taking the motion language to be used from the motion language accumulator. The motion patterns are executed to express the intentions and details of communication.
In one form of the first aspect of the present invention, the articulated robot further includes an external interface used for performing operations including an image input operation, a sound input/output operation, and a data transmission/reception operation through a communications medium, and a communication controller for controlling the communication based on input/output data through the external interface. In the articulated robot, the communication controller determines the motion language to be used in accordance with the details of the communication.
In another form of the first aspect of the present invention, the motion language is realized using a method which forms a sentence by repeating the formation of a plurality of characters with the basic mode of formation being in character units, or by using a method which realizes the communication by a motion which has a meaning or based on a time-series change in a joint angle.
In still another form of the first aspect of the present invention, a plurality of motion languages are combined to express the intentions of the robot or the details of the communication. In addition, the motion language accumulator includes a motion pattern used to direct the starting of the realization of the motion language, and/or a motion pattern used to direct the ending of the realization of the motion language. For example, the starting and the ending of the realization of the motion language can be indicated by the raising of the right hand and the left hand of the humanoid robot. By executing the motion patterns thereof in starting and ending the communication, the observer of the motion language can easily and reliably recognize the motion language.
In still another form of the first aspect of the present invention, when a plurality of motion languages are combined to express the intentions of the robot or the details of the communication, the motion language accumulator includes a motion pattern used for directing the provision of a delimiter between the motion languages. By executing such a motion pattern for a delimiter between motion languages, the observer of the motion language can recognize the motion language without becoming confused.
In still another form of the first aspect of the present invention, the articulated robot further includes a movement teaching section for directly teaching the motion pattern which is executed to realize the motion language as a result of directly holding and operating each of the joints.
In still another form of the first aspect of the present invention, the articulated robot further includes a movement teaching section for indirectly teaching the motion pattern which is executed to realize the motion language as a result of actuating each of the joints along a coordinate system of the robot.
According to a second aspect of the present invention, there is provided method of controlling the motion of an articulated robot which comprises a plurality of joints and which accumulates a motion language which is formed by a motion pattern of each of the joints used to express the intentions of the robot and the details of communication. The method comprises the steps of determining the motion language to be used, and controlling the movement of each of the joints for realizing the determined motion language.
In one form of the second aspect of the present invention, the method further comprises the steps of inputting and outputting data to the outside through a communications medium and of controlling communication based on the data input/output operation. In the method, the motion language to be used is determined in accordance with the details of the communication. In addition, the inputting and outputting of data includes inputting of an image, inputting/outputting of sound, and transmitting/receiving of data.
In still another form of the second aspect of the present invention, the method further comprises the step of executing a motion pattern used to direct the starting of the realization of the motion language and/or the step of executing the motion pattern used to direct the ending of the realization of the motion language. For example, the starting and the ending of the realization of the motion language can be indicated by the raising of the right hand and the left hand of the humanoid robot. By executing the motion patterns thereof in starting and ending the communication, the observer of the motion language can easily and reliably recognize the motion language.
In still another form of the second aspect of the present invention, the method comprises the step of, when the intentions of the robot or details of the communication are expressed by combining a plurality of the motion languages, executing a motion pattern used to direct the provision of a delimiter between the motion languages. By inserting a motion pattern for a delimiter between motion languages, the observer of the motion languages can recognize the motion pattern without becoming confused.
In still another form of the second aspect of the present invention, the method further comprises the step of directly teaching the motion pattern which is executed to realize the motion language as a result of directly holding and operating each of the joints.
In still another form of the second aspect of the present invention, the method comprises the step of indirectly teaching the motion pattern which is executed to realize the motion language as a result of actuating each of the joints along a coordinate system of the robot.
The present invention is widely applicable to an articulated robot comprising a plurality of joints. More preferably, it is applicable to a legged mobile robot such as a humanoid robot which has relatively long arms and legs and which can execute a motion pattern which is highly expressive of emotions and feelings.
A humanoid robot can realize a motion language by executing a motion pattern using the four limbs and the trunk or a time-series change in a joint angle. Here, xe2x80x9cmotion languagexe2x80x9d refers to a pseudolanguage used to express the intentions of the robot and the details of the communication to an external device or a user by using a predetermined motion pattern of the four limbs and the trunk. The motion language makes it possible to transmit information without using any digital data such as a program code and a communications code. The motion language is based on, for example, a method in which the basic formation mode is in character units, and the robot 100 repeatedly forms a plurality of characters in order to form a sentence, or a method in which communication is realized by a motion which has a meaning or based on a time-series change in a joint angle.
By using the motion language which is made up of, for example, a motion pattern which is an approximation of the contour/form of a character, it can be visually recognized and interpreted. By visually recognizing and interpreting the contour/form which is represented by the motion pattern, the meaning and character represented by each motion pattern can be determined even by a human being or a robot which does not possess the same motion language database.
For example, when the robot steps into a dangerous working area, it can give a message, such as the condition of the working area, to an observer at a remote place without using any data communications means.